Huh. Apparently phpBB does not fully support BBCode as it's defined. Since we won't be radically changing the board software anytime soon, the best I could do is offer an alternate BBCode tag that does allow for alt text. Maybe.

Alright, it works. Use the pix tag if you want to post an image with alt text. You must add alt text if you use the pix tag or else it won't work right. It'll stick around until I'm tired of answering questions about the pix tag.